TO USE :

Put this folder into C:\Users[User]\Documents\Paradox Interactive\Stellaris\mod\
Put the file "customCivics.mod" in C:\Users[User]\Documents\Paradox Interactive\Stellaris\mod\

Launch stellaris launcher and activate this mod.

Troubleshooting : If this mod doesn't show up in the list :
make sure this folder and the .mod is in the right place (both in \mod)

If you have some problems, look at the error.log in :
C:\Users[User]\Documents\Paradox Interactive\Stellaris\logs\